Peroxymonosulfate (PMS) activation on cobalt-doped TiO₂ nanotubes: degradation of organics under dark and solar light irradiation conditions

Peroxymonosulfate activation on cobalt-doped TiO₂ nanotubes (Co-TNTs) as applied for the degradation of organic pollutants in the absence of light and under solar light irradiation is investigated. Co-TNTs generate SO₄˙⁻ via PMS activation in the dark, while they result in SO₄˙⁻ formation via PMS activation and, at the same time, produce ˙OH via photocatalytic water oxidation under simulated solar light illumination. Radical generation is explored using electron paramagnetic resonance (EPR) spectroscopy. The catalytic activity is maintained over multiple catalytic cycles with negligible Co(II) leaching. The nanotube catalysts are easily recovered without loss of activity after water treatment. The Co-TNT/PMS reaction system can be used for wastewater treatment during the day and at night.